This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The use of deep brain stimulation (DBS) of the sub thalamic nuclei (STN) to treat Parkinson's disease (PD) provides a reversible means of modifying the activity of sub cortical areas. While effective in reducing non speech motor symptoms, this form of therapy often has no effect or even a negative effect on speech, raising questions about the relationship between speech and non speech motor control in PD. Using functional imaging and quantifiable speech production tasks, this project proposes to study the relationships between brain activity in cortical and subcortical regions in subjects with PD, in subjects with PD treated by DBS, and in normal controls. The goal is to better understand cortical subcortical interactions in normal and disordered speech, and the role of such interactions in specific aspects of speech production. Regional cerebral blood flow will be measured during several speech production tasks using positron emission tomography (PET) to address four primary specific aims. The first primary specific aim focuses on the relationships between cortical and subcortical areas during speech production in normal subjects. The second primary specific aim focuses on the relationships between cortical and subcortical areas during speech production in PD subjects. The third primary specific aim focuses on the relationships between cortical and subcortical areas during speech production in PD subjects treated with bilateral DBS of the sub-thalamic nuclei. The fourth primary specific aim is to examine and compare the relationships between specific characteristics of speech production and regional cerebral blood flow.